Marquardt joined the U.S. foreign service in 1980. He served as the U.S. Ambassador to the Republic of
Madagascar and the Union of the
Comoros from 2007 to 2010. He was nominated by President
George W. Bush on March 26, 2007. On May 25, 2007, the Senate confirmed his nomination. He was sworn in on August 17, 2007. He also served as the U.S. Ambassador to the Republic of
Cameroon from 2004 to 2007 and as U.S. Ambassador to the Republic of
Equatorial Guinea from 2004 to 2006. From 2001 to 2004, he served as the Special Coordinator for Diplomatic Readiness. In this role, he was responsible for coordinating the largest increase in State Department recruiting, hiring, and training in its history. A senior Foreign Service officer, class of Minister-Counselor, he also served in 1998 to 2000 as Director of the Department's Entry-level Counseling and Assignments Division in the Bureau of Human Resources. Marquardt's overseas assignments as an economic officer have taken him to
Germany (1995–98),
France (1990–94),
Thailand twice (1981–83, 1987–90) and
Brazzaville,
Congo (1983–85). He also served mainly in the Bureau of East Asian and Pacific Affairs and as a Country Risk Analyst at the
Export-Import Bank of the United States. Additionally, he attended the
Senior Seminar and the Economic-Commercial Studies Program at the Department's
Foreign Service Institute. ==Awards and honours==